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ext4: refactor sysfs support code
authorTheodore Ts'o <tytso@mit.edu>
Wed, 23 Sep 2015 16:45:17 +0000 (12:45 -0400)
committerTheodore Ts'o <tytso@mit.edu>
Wed, 23 Sep 2015 16:45:17 +0000 (12:45 -0400)
Make the code more easily extensible as well as taking up less
compiled space.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
fs/ext4/sysfs.c

index 9fdc21b..87ac089 100644 (file)
 #include "ext4.h"
 #include "ext4_jbd2.h"
 
+typedef enum {
+       attr_noop,
+       attr_delayed_allocation_blocks,
+       attr_session_write_kbytes,
+       attr_lifetime_write_kbytes,
+       attr_reserved_clusters,
+       attr_inode_readahead,
+       attr_trigger_test_error,
+       attr_feature,
+       attr_pointer_ui,
+       attr_pointer_atomic,
+} attr_id_t;
+
+typedef enum {
+       ptr_explicit,
+       ptr_ext4_sb_info_offset,
+       ptr_ext4_super_block_offset,
+} attr_ptr_t;
+
 struct ext4_attr {
        struct attribute attr;
-       ssize_t (*show)(struct ext4_attr *, struct ext4_sb_info *, char *);
-       ssize_t (*store)(struct ext4_attr *, struct ext4_sb_info *,
-                        const char *, size_t);
+       short attr_id;
+       short attr_ptr;
        union {
                int offset;
-               int deprecated_val;
+               void *explicit_ptr;
        } u;
 };
 
-static int parse_strtoull(const char *buf,
-               unsigned long long max, unsigned long long *value)
-{
-       int ret;
-
-       ret = kstrtoull(skip_spaces(buf), 0, value);
-       if (!ret && *value > max)
-               ret = -EINVAL;
-       return ret;
-}
-
-static ssize_t delayed_allocation_blocks_show(struct ext4_attr *a,
-                                             struct ext4_sb_info *sbi,
-                                             char *buf)
-{
-       return snprintf(buf, PAGE_SIZE, "%llu\n",
-               (s64) EXT4_C2B(sbi,
-                       percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
-}
-
 static ssize_t session_write_kbytes_show(struct ext4_attr *a,
                                         struct ext4_sb_info *sbi, char *buf)
 {
@@ -89,46 +87,6 @@ static ssize_t inode_readahead_blks_store(struct ext4_attr *a,
        return count;
 }
 
-static ssize_t sbi_ui_show(struct ext4_attr *a,
-                          struct ext4_sb_info *sbi, char *buf)
-{
-       unsigned int *ui = (unsigned int *) (((char *) sbi) + a->u.offset);
-
-       return snprintf(buf, PAGE_SIZE, "%u\n", *ui);
-}
-
-static ssize_t sbi_ui_store(struct ext4_attr *a,
-                           struct ext4_sb_info *sbi,
-                           const char *buf, size_t count)
-{
-       unsigned int *ui = (unsigned int *) (((char *) sbi) + a->u.offset);
-       unsigned long t;
-       int ret;
-
-       ret = kstrtoul(skip_spaces(buf), 0, &t);
-       if (ret)
-               return ret;
-       *ui = t;
-       return count;
-}
-
-static ssize_t es_ui_show(struct ext4_attr *a,
-                          struct ext4_sb_info *sbi, char *buf)
-{
-
-       unsigned int *ui = (unsigned int *) (((char *) sbi->s_es) +
-                          a->u.offset);
-
-       return snprintf(buf, PAGE_SIZE, "%u\n", *ui);
-}
-
-static ssize_t reserved_clusters_show(struct ext4_attr *a,
-                                 struct ext4_sb_info *sbi, char *buf)
-{
-       return snprintf(buf, PAGE_SIZE, "%llu\n",
-               (unsigned long long) atomic64_read(&sbi->s_resv_clusters));
-}
-
 static ssize_t reserved_clusters_store(struct ext4_attr *a,
                                   struct ext4_sb_info *sbi,
                                   const char *buf, size_t count)
@@ -136,11 +94,10 @@ static ssize_t reserved_clusters_store(struct ext4_attr *a,
        unsigned long long val;
        ext4_fsblk_t clusters = (ext4_blocks_count(sbi->s_es) >>
                                 sbi->s_cluster_bits);
+       int ret;
 
-       if (parse_strtoull(buf, -1ULL, &val))
-               return -EINVAL;
-
-       if (val >= clusters)
+       ret = kstrtoull(skip_spaces(buf), 0, &val);
+       if (!ret || val >= clusters)
                return -EINVAL;
 
        atomic64_set(&sbi->s_resv_clusters, val);
@@ -164,60 +121,51 @@ static ssize_t trigger_test_error(struct ext4_attr *a,
        return count;
 }
 
-static ssize_t sbi_deprecated_show(struct ext4_attr *a,
-                                  struct ext4_sb_info *sbi, char *buf)
-{
-       return snprintf(buf, PAGE_SIZE, "%d\n", a->u.deprecated_val);
+#define EXT4_ATTR(_name,_mode,_id)                                     \
+static struct ext4_attr ext4_attr_##_name = {                          \
+       .attr = {.name = __stringify(_name), .mode = _mode },           \
+       .attr_id = attr_##_id,                                          \
 }
 
-#define EXT4_ATTR_OFFSET(_name,_mode,_show,_store,_elname) \
+#define EXT4_ATTR_FUNC(_name,_mode)  EXT4_ATTR(_name,_mode,_name)
+
+#define EXT4_ATTR_FEATURE(_name)   EXT4_ATTR(_name, 0444, feature)
+
+#define EXT4_ATTR_OFFSET(_name,_mode,_id,_struct,_elname)      \
 static struct ext4_attr ext4_attr_##_name = {                  \
        .attr = {.name = __stringify(_name), .mode = _mode },   \
-       .show   = _show,                                        \
-       .store  = _store,                                       \
+       .attr_id = attr_##_id,                                  \
+       .attr_ptr = ptr_##_struct##_offset,                     \
        .u = {                                                  \
-               .offset = offsetof(struct ext4_sb_info, _elname),\
+               .offset = offsetof(struct _struct, _elname),\
        },                                                      \
 }
 
-#define EXT4_ATTR_OFFSET_ES(_name,_mode,_show,_store,_elname)          \
-static struct ext4_attr ext4_attr_##_name = {                          \
-       .attr = {.name = __stringify(_name), .mode = _mode },           \
-       .show   = _show,                                                \
-       .store  = _store,                                               \
-       .u = {                                                          \
-               .offset = offsetof(struct ext4_super_block, _elname),   \
-       },                                                              \
-}
-
-#define EXT4_ATTR(name, mode, show, store) \
-static struct ext4_attr ext4_attr_##name = __ATTR(name, mode, show, store)
-
-#define EXT4_INFO_ATTR(name) EXT4_ATTR(name, 0444, NULL, NULL)
-#define EXT4_RO_ATTR(name) EXT4_ATTR(name, 0444, name##_show, NULL)
-#define EXT4_RW_ATTR(name) EXT4_ATTR(name, 0644, name##_show, name##_store)
+#define EXT4_RO_ATTR_ES_UI(_name,_elname)                              \
+       EXT4_ATTR_OFFSET(_name, 0444, pointer_ui, ext4_super_block, _elname)
 
-#define EXT4_RO_ATTR_ES_UI(name, elname)       \
-       EXT4_ATTR_OFFSET_ES(name, 0444, es_ui_show, NULL, elname)
-#define EXT4_RW_ATTR_SBI_UI(name, elname)      \
-       EXT4_ATTR_OFFSET(name, 0644, sbi_ui_show, sbi_ui_store, elname)
+#define EXT4_RW_ATTR_SBI_UI(_name,_elname)     \
+       EXT4_ATTR_OFFSET(_name, 0644, pointer_ui, ext4_sb_info, _elname)
 
-#define ATTR_LIST(name) &ext4_attr_##name.attr
-#define EXT4_DEPRECATED_ATTR(_name, _val)      \
+#define EXT4_ATTR_PTR(_name,_mode,_id,_ptr) \
 static struct ext4_attr ext4_attr_##_name = {                  \
-       .attr = {.name = __stringify(_name), .mode = 0444 },    \
-       .show   = sbi_deprecated_show,                          \
+       .attr = {.name = __stringify(_name), .mode = _mode },   \
+       .attr_id = attr_##_id,                                  \
+       .attr_ptr = ptr_explicit,                               \
        .u = {                                                  \
-               .deprecated_val = _val,                         \
+               .explicit_ptr = _ptr,                           \
        },                                                      \
 }
 
-EXT4_RO_ATTR(delayed_allocation_blocks);
-EXT4_RO_ATTR(session_write_kbytes);
-EXT4_RO_ATTR(lifetime_write_kbytes);
-EXT4_RW_ATTR(reserved_clusters);
-EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, sbi_ui_show,
-                inode_readahead_blks_store, s_inode_readahead_blks);
+#define ATTR_LIST(name) &ext4_attr_##name.attr
+
+EXT4_ATTR_FUNC(delayed_allocation_blocks, 0444);
+EXT4_ATTR_FUNC(session_write_kbytes, 0444);
+EXT4_ATTR_FUNC(lifetime_write_kbytes, 0444);
+EXT4_ATTR_FUNC(reserved_clusters, 0644);
+
+EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, inode_readahead,
+                ext4_sb_info, s_inode_readahead_blks);
 EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal);
 EXT4_RW_ATTR_SBI_UI(mb_stats, s_mb_stats);
 EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan);
@@ -225,9 +173,8 @@ EXT4_RW_ATTR_SBI_UI(mb_min_to_scan, s_mb_min_to_scan);
 EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs);
 EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
 EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc);
-EXT4_DEPRECATED_ATTR(max_writeback_mb_bump, 128);
 EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb);
-EXT4_ATTR(trigger_fs_error, 0200, NULL, trigger_test_error);
+EXT4_ATTR(trigger_fs_error, 0200, trigger_test_error);
 EXT4_RW_ATTR_SBI_UI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval);
 EXT4_RW_ATTR_SBI_UI(err_ratelimit_burst, s_err_ratelimit_state.burst);
 EXT4_RW_ATTR_SBI_UI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval);
@@ -238,6 +185,9 @@ EXT4_RO_ATTR_ES_UI(errors_count, s_error_count);
 EXT4_RO_ATTR_ES_UI(first_error_time, s_first_error_time);
 EXT4_RO_ATTR_ES_UI(last_error_time, s_last_error_time);
 
+static unsigned int old_bump_val = 128;
+EXT4_ATTR_PTR(max_writeback_mb_bump, 0444, pointer_ui, &old_bump_val);
+
 static struct attribute *ext4_attrs[] = {
        ATTR_LIST(delayed_allocation_blocks),
        ATTR_LIST(session_write_kbytes),
@@ -267,10 +217,10 @@ static struct attribute *ext4_attrs[] = {
 };
 
 /* Features this copy of ext4 supports */
-EXT4_INFO_ATTR(lazy_itable_init);
-EXT4_INFO_ATTR(batched_discard);
-EXT4_INFO_ATTR(meta_bg_resize);
-EXT4_INFO_ATTR(encryption);
+EXT4_ATTR_FEATURE(lazy_itable_init);
+EXT4_ATTR_FEATURE(batched_discard);
+EXT4_ATTR_FEATURE(meta_bg_resize);
+EXT4_ATTR_FEATURE(encryption);
 
 static struct attribute *ext4_feat_attrs[] = {
        ATTR_LIST(lazy_itable_init),
@@ -280,14 +230,56 @@ static struct attribute *ext4_feat_attrs[] = {
        NULL,
 };
 
+static void *calc_ptr(struct ext4_attr *a, struct ext4_sb_info *sbi)
+{
+       switch (a->attr_ptr) {
+       case ptr_explicit:
+               return a->u.explicit_ptr;
+       case ptr_ext4_sb_info_offset:
+               return (void *) (((char *) sbi) + a->u.offset);
+       case ptr_ext4_super_block_offset:
+               return (void *) (((char *) sbi->s_es) + a->u.offset);
+       }
+       return NULL;
+}
+
 static ssize_t ext4_attr_show(struct kobject *kobj,
                              struct attribute *attr, char *buf)
 {
        struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
                                                s_kobj);
        struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);
-
-       return a->show ? a->show(a, sbi, buf) : 0;
+       void *ptr = calc_ptr(a, sbi);
+
+       switch (a->attr_id) {
+       case attr_delayed_allocation_blocks:
+               return snprintf(buf, PAGE_SIZE, "%llu\n",
+                               (s64) EXT4_C2B(sbi,
+                      percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
+       case attr_session_write_kbytes:
+               return session_write_kbytes_show(a, sbi, buf);
+       case attr_lifetime_write_kbytes:
+               return lifetime_write_kbytes_show(a, sbi, buf);
+       case attr_reserved_clusters:
+               return snprintf(buf, PAGE_SIZE, "%llu\n",
+                               (unsigned long long)
+                               atomic64_read(&sbi->s_resv_clusters));
+       case attr_inode_readahead:
+       case attr_pointer_ui:
+               if (!ptr)
+                       return 0;
+               return snprintf(buf, PAGE_SIZE, "%u\n",
+                               *((unsigned int *) ptr));
+       case attr_pointer_atomic:
+               if (!ptr)
+                       return 0;
+               return snprintf(buf, PAGE_SIZE, "%d\n",
+                               atomic_read((atomic_t *) ptr));
+       case attr_feature:
+               return snprintf(buf, PAGE_SIZE, "supported\n");
+       }
+
+       return 0;
 }
 
 static ssize_t ext4_attr_store(struct kobject *kobj,
@@ -297,8 +289,27 @@ static ssize_t ext4_attr_store(struct kobject *kobj,
        struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
                                                s_kobj);
        struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);
+       void *ptr = calc_ptr(a, sbi);
+       unsigned long t;
+       int ret;
 
-       return a->store ? a->store(a, sbi, buf, len) : 0;
+       switch (a->attr_id) {
+       case attr_reserved_clusters:
+               return reserved_clusters_store(a, sbi, buf, len);
+       case attr_pointer_ui:
+               if (!ptr)
+                       return 0;
+               ret = kstrtoul(skip_spaces(buf), 0, &t);
+               if (ret)
+                       return ret;
+               *((unsigned int *) ptr) = t;
+               return len;
+       case attr_inode_readahead:
+               return inode_readahead_blks_store(a, sbi, buf, len);
+       case attr_trigger_test_error:
+               return trigger_test_error(a, sbi, buf, len);
+       }
+       return 0;
 }
 
 static void ext4_sb_release(struct kobject *kobj)
@@ -327,25 +338,9 @@ static struct kset ext4_kset = {
        .kobj   = {.ktype = &ext4_ktype},
 };
 
-static ssize_t ext4_feat_show(struct kobject *kobj,
-                             struct attribute *attr, char *buf)
-{
-       return snprintf(buf, PAGE_SIZE, "supported\n");
-}
-
-/*
- * We can not use ext4_attr_show/store because it relies on the kobject
- * being embedded in the ext4_sb_info structure which is definitely not
- * true in this case.
- */
-static const struct sysfs_ops ext4_feat_ops = {
-       .show   = ext4_feat_show,
-       .store  = NULL,
-};
-
 static struct kobj_type ext4_feat_ktype = {
        .default_attrs  = ext4_feat_attrs,
-       .sysfs_ops      = &ext4_feat_ops,
+       .sysfs_ops      = &ext4_attr_ops,
 };
 
 static struct kobject ext4_feat = {